As with any macro lens, one cannot assume that peak performance will be reached at infinity; as a macro lens one might properly expect that performance has been optimized for close-range focusing.

Quick summary

Overall optimal aperture appears to be ƒ/6.7, with ƒ/5.6 showing weak corners yielding a nice pop to ƒ/6.7. While ƒ/8 shows a slight loss of micro contrast, it is also a very good choice for a little more depth of field. Stopping down beyond ƒ/8 even 1/2 stop to ƒ/9.5 quickly degrades image contrast.

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